Congress ordered nationwide rail safety measures in 2008 that may have prevented Sunday’s Metro-North tragedy — but the MTA wants to delay implementation because of technological hurdles.

The law requires commuter railroads across the country to install by 2015 a system called positive train control, which can reduce a train’s speed through a computer in emergency situations.

“For more than 20 years, the NTSB has recommended the use of positive train control technology,” said board member Earl Weener at a press conference about the Bronx derailment.

“It’s possible positive train control could have prevented it.”

The law was passed after a horrific 2008 California train crash where an engineer blew a red signal while texting, killing 25 people.

The MTA has sought a three-year extension to implement PTC, which will cost almost $1 billion.

“Much of the technology is still under development and is untested and unproven for commuter railroads the size and complexity of Metro-North and LIRR,” the MTA said in a statement on Tuesday, noting that the radio spectrum necessary to operate it isn’t available yet.

Many railroads have opposed installing PTC because of the high costs and huge technological challenges of using radio, GPS and Wi-Fi to track the locations of trains and their speed.

“It’s very expensive. I know it’s been controversial,” Gov. Cuomo said on WNYC radio. “But there’s no doubt that there are electronic systems that can help a train operate.”

So far only Amtrak has installed PTC, using it on sharp curves and other sections in its Northeast Corridor.